The invention had the object of finding novel compounds having valuable properties, in particular those which can be used for the preparation of medicaments.
The present invention relates to imidazopyrazinone derivatives which inhibit the activity of Tankyrases (TANKs) and poly(ADP-ribose)polymerase PARP-1. The compounds of this invention are therefore useful in treating diseases such as cancer, multiple sclerosis, cardiovascular diseases, central nervous system injury and different forms of inflammation. The present invention also provides methods for preparing these compounds, pharmaceutical compositions comprising these compounds, and methods of treating diseases utilizing pharmaceutical compositions comprising these compounds.
The nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) is a member of the PARP enzyme family. This growing family of enzymes consist of PARPs such as, for example: PARP-1, PARP-2, PARP-3 and Vault-PARP; and Tankyrases (TANKs), such as, for example: TANK-1 and TANK-2. PARP is also referred to as poly(adenosine 5′-diphospho-ribose) polymerase or PARP (poly(ADP-ribose) synthetase).
TANK-1 seems to be required for the polymerization of mitotic spindle-associated poly(ADP-ribose). The poly(ADP-ribosyl)ation activity of TANK-1 might be crucial for the accurate formation and maintenance of spindle bipolarity. Furthermore, PARP activity of TANK-1 has been shown to be required for normal telomere separation before anaphase. Interference with tankyrase PARP activity results in aberrant mitosis, which engenders a transient cell cycle arrest, probably due to spindle checkpoint activation, followed by cell death. Inhibition of tankyrases is therefore expected to have a cytotoxic effect on proliferating tumor cells (WO 2008/107478).
PARP inhibitors are described by M. Rouleau et al. in Nature Reviews, Volume 10, 293-301 in clinical cancer studies (Table 2, page 298).
According to a review by Horvath and Szabo (Drug News Perspect 20(3), April 2007, 171-181) most recent studies demonstrated that PARP inhibitors enhance the cancer cell death primarily because they interfere with DNA repair on various levels. More recent studies have also demonstrated that PARP inhibitors inhibit angiogenesis, either by inhibiting growth factor expression, or by inhibiting growth factor-induced cellular proliferative responses. These findings might also have implications on the mode of PARP inhibitors' anticancer effects in vivo.
Also a study by Tentori et al. (Eur. J. Cancer, 2007, 43 (14) 2124-2133) shows that PARP inhibitors abrogate VEGF or placental growth factor-induced migration and prevent formation of tubule-like networks in cell-based systems, and impair angiogenesis in vivo. The study also demonstrates that growth factor-induced angiogenesis is deficient in PARP-1 knock-out mice. The results of the study provide evidence for targeting PARP for anti-angiogenesis, adding novel therapeutic implications to the use of PARP inhibitors in cancer treatment.
Defects in conserved signaling pathways are well known to play key roles in the origins and behavior of essentially all cancers (E. A. Fearon, Cancer Cell, Vol. 16, Issue 5, 2009, 366-368). The Wnt pathway is a target for anti-cancer therapy. A key feature of the Wnt pathway is the regulated proteolysis (degradation) of β-catenin by the β-catenin destruction complex. Proteins like WTX, APC or Axin are involved in the degradation process. A proper degradation of β-catenin is important to avoid an inappropriate activation of the Wnt pathway which has been observed in many cancers. Tankyrases inhibit activity of Axin and hence inhibit the degradation of β-catenin. Consequently, tankyrase inhibitors increase degradation of β-catenin. A paper in the journal Nature not only offers important new insights into proteins regulating Wnt signaling but also further supports the approach to antagonize β-catenin levels and localization via small molecules (Huang et al., 2009; Nature, Vol 461, 614-620). The compound XAV939 inhibits growth of DLD-1-cancer cells. They found that XAV9393 blocked Wnt-stimulated accumulation of β-catenin by increasing the levels of the AXIN1 and AXIN2 proteins. Subsequent work by the authors established that XAV939 regulates AXIN levels via inhibition of tankyrases 1 and 2 (TNKS1 and TNKS2), both of which are members of the poly(ADP-ribose) polymerase (PARP) protein family (S. J. Hsiao et al. Biochimie 90, 2008, 83-92).
It has been found that the compounds according to the invention and salts thereof have very valuable pharmacological properties while being well tolerated.
The present invention specifically relates to compounds of the formula I which inhibit Tankyrase 1 and 2, to compositions which comprise these compounds, and to processes for the use thereof for the treatment of TANK-induced diseases and complaints.
The compounds of the formula I can furthermore be used for the isolation and investigation of the activity or expression of TANKs. In addition, they are particularly suitable for use in diagnostic methods for diseases in connection with unregulated or disturbed TANK activity.
The host or patient can belong to any mammalian species, for example a primate species, particularly humans; rodents, including mice, rats and hamsters; rabbits; horses, cows, dogs, cats, etc. Animal models are of interest for experimental investigations, providing a model for treatment of human disease.
The susceptibility of a particular cell to treatment with the compounds according to the invention can be determined by in vitro tests. Typically, a culture of the cell is combined with a compound according to the invention at various concentrations for a period of time which is sufficient to allow active agents such as anti IgM to induce a cellular response such as expression of a surface marker, usually between about one hour and one week. In vitro testing can be carried out using cultivated cells from blood or from a biopsy sample. The amount of surface marker expressed is assessed by flow cytometry using specific antibodies recognising the marker.
The dose varies depending on the specific compound used, the specific disease, the patient status, etc. A therapeutic dose is typically sufficient considerably to reduce the undesired cell population in the target tissue while the viability of the patient is maintained. The treatment is generally continued until a considerable reduction has occurred, for example an at least about 50% reduction in the cell burden, and may be continued until essentially no more undesired cells are detected in the body.